February 10, 2005

Pretty Devastation

A seabed survey conducted by scientists abord the oceanographic research ship HMS Scott has mapped a new undersea ridge near the epicenter of the December 2004 Indonesian earthquake.

Slabs of rock weighing millions of tonnes were dragged up to 10 kilometres along the seabed by the force of the displaced water. And while mountainous ridges 1,500 metres tall were forged from debris during the huge movement of earth, an oceanic trench several kilometres wide was ripped open.

The first results have yielded far more than the scientists had hoped for. Coloured contour maps of the seabed clearly show the boundary between the deep, flat Indian Plate, and the heavily deformed edge of the Burman Plate (boundary marked on images with a white dashed line). The collision has forced up spectacular large thrust ridges up to 1500 m high, higher than Ben Nevis. These unstable blocks have collapsed in places, producing large landslides several kilometres across that have scarred the seafloor.

There's a powerpoint presentation on the various discoveries by the Scott in the area here. Be forewarned, it's big (36 MB). However, it's well worth the wait, at least to me it was, and contains a number of the false color sonar images like the one above.

In other earthquake related news, the intial strength estimates for the December quake (9.0 on the Richter scale) were too low. It's now considered to have been a 9.3 quake, three times stronger than initially thought, making it the second most powerful earthquake ever recorded.

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Comments

Too lazy to look, but has not the Richter scale been superseded by the earthquake readings in magnitudes which doubtless correlate to Richter the way Parts per Million pretty much equal Milligrams per Liter?